Can a USB cable suffer from ‘interference’?
how does interference effect XLR and USB audio cables and does it effect them differently
Can someone explain the difference and preferably post sources for me as well?
In: Engineering
XLR is analog, USB is digital. XLR cables are typically used to transmit audio data as a variable voltage that directly corresponds to the sound wave. USB is a digital standard, transmitting data as numbers encoded as a series of 1s and 0s, corresponding to on and off.
Electromagnetic interference is caused when cables and other equipment act like antennas, and electromagnetic radiation induces electromotive force or voltage in them. Interference picked up in this fashion normally looks like noise – random information that changes in an unpredictable manner.
USB is digital, there are only two meaningful values – 0 and 1, on and off. If the interference isn’t strong enough to make a 1 look like a 0 or make a 0 look like a 1, then it doesn’t really affect its ability to communicate information accurately. Interference can be filtered out from USB cables using a ferrite bead, which makes the cable act like an inductor to block out rapid changes to the signal.
Because audio transmitted over XLR is analog and even little changes to the voltage can make an audible difference (especially if it’s a “quiet” signal that will be amplified a lot before you hear it), it cannot simply ignore weak interference. However, XLR cables often have measures to reduce or block interference. Shielded cables have a grounded conductive sheath surrounding the signal-carrying wires, with the idea that the shield picks up the interference (and dissipates it) instead of the conductors inside. Balanced signals are common too, which sends two copies of the signal with opposite polarity (and ground, which is why XLR has 3 conductors), and the device receiving the signal takes their difference – noise picked up from interference will be mostly the same in both copies, so it gets canceled out.
I know quite a bit about audio circuitry but interference is not my strongest area. If I said anything that’s inaccurate, or if anyone has something to add, please reply!
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